This invention relates to a novel method of manufacturing a fabric article to include electronic circuitry and to an electrically active textile article useful, for example, in the fields of wearable circuitry and wearable computers, medical sensors and novelty devices.
The idea of xe2x80x9cwearablexe2x80x9d circuitry and xe2x80x9cwearablexe2x80x9d computers is not new. U.S. Pat. No. 6,210,771, incorporated herein by this reference, discloses fabrics with integral circuits in that select fibers of the fabric are conductive creating electrical pathways. Electronic components are then soldered to the conductive fibers in the fabric some of which must be cut to avoid unwanted electrical connections. Also, since the conductive fibers are constrained to run only in the weft direction, the electronic components to be electrically interconnected to the weft direction conductive fibers are constrained in their arrangement.
Also in the prior art is the idea of a rigid circuit board placed on a fabric article and housed thereon in a polymer shell. The problem with this design is that the circuit board is not in intimate contact with the fabric and, in addition, the polymer shell protrudes from the fabric article limiting its usefulness and also limiting the maximum size of the rigid circuit board.
It is therefore an object of this invention to provide textile based wearable and even non-wearable circuitry which does not require any modification to the fabric article.
It is a further object of this invention to provide a method of manufacturing a fabric article to include electronic circuitry which eliminates the need for conductive fibers in the fabric and the need to cut select conductive fibers to avoid unwanted electrical connections.
It is a further object of this invention to provide an electrically active textile article in which the position and arrangement of the various electronic components are not constrained.
It is a further object of this invention to avoid the use of rigid circuit boards.
It is a further object of this invention to provide a comfortable, waterproof, washable, low-profile, and flexible circuit addition to the fabric of an article of clothing.
This invention results from the realization that by employing a circuit typically embodied in a flex circuit secured to fabric, the need for conductive fibers in the fabric is eliminated, the position and arrangement of the various electronic components are not constrained, and, instead, the result is a comfortable, waterproof, washable, low-profile, and flexible wearable circuit.
This invention features a method of manufacturing a fabric article to include electronic circuitry. The preferred method comprises assembling a circuit, typically a flex circuit, to include electrically conductive or merely decorative traces and pads on a flexible substrate, placing a fabric article on a rigid surface, and securing the substrate of the flex circuit to the fabric article.
In the preferred embodiment, an ultrasonic device, such as a handheld ultrasonic horn, is used to weld the substrate to the fabric. The rigid surface may be made of stainless steel. In other embodiments, an adhesive is used to fix the substrate on the fabric. In still another embodiment, the substrate is sewn to the fabric and a layer of additional material may be inserted between the substrate and the fabric to reinforce the stitch area. Also, in the preferred embodiment, a water proof protective covering is secured over the flex circuit. In one example, this protective covering extends onto the fabric.
The flex circuit may be populated with electronic components before or even after the substrate is secured to the fabric. In one embodiment, the flexible substrate is a thermoplastic material and the conductive traces and pads are metal. The fabric maybe selected from the group consisting of woven, knit, non-woven, and braided fabrics. The fabric is typically a portion of a wearable article or other useable articles.
Preferably, stress relief areas are formed in the flex circuit to promote flexure of the flex circuit. The stress relief areas may be cut-outs in edges of the flex circuit, cut-outs through the flex circuit, channels formed in the flex circuit, and/or material (e.g., a polymer) added to the substrate of the flex circuit. Typically, the stress relief areas are located between electronic components on the flex circuit.
In one example, two flex circuits are secured to the fabric and electrically interconnected. The two flex circuits may be secured and electrically interconnected by a zipper or a pair of VELCRO(copyright) patches, portions of which are conductive to provide the electrical interconnections. The flex circuits may include conductive solder pads thereon, and the fabric may be a polyester-coated copper fabric. The solder pads and the polyester coating are melted to provide the electrical interconnections.
Preferably, the flex circuit includes a perimeter bond area devoid of conductive traces and pads and the step of securing then typically includes fixing the perimeter bond area of the flex circuit to the fabric. Perimeter reinforcement may be provided by a perimeter area including material added to the substrate.
This invention also features an electrically active textile article. A flex circuit including conductive traces and pads on a flexible substrate is secured to the fabric and at least one electronic component populates the flex circuit. The flex circuit substrate may be ultrasonically welded to the fabric about the periphery of the substrate which, in one example, includes a perimeter bond area devoid of conductive traces and pads. An adhesive may also be used to secure the flexible substrate to the fabric. Alternatively, threads secure the flexible substrate to the fabric.
In the preferred embodiment, a waterproof protective covering extends over the flex circuit. The protective covering may further extend onto the fabric itself.
In one example, the flexible substrate is made of a thermoplastic material and the conductive traces and pads are metal. The fabric may be selected from the group consisting of woven, knit, non-woven, and braided fabrics. In many cases, the fabric is a portion of a wearable article.
Preferably, stress relief areas in the flex circuit promote flexure of the flex circuit. The stress relief areas may be cut-outs in the edges of the flex circuit, cut-outs through the flex circuit, channels formed in the flex circuit, or material added to the flex circuit substrate. Typically, the stress relief areas are located between electronic components on the flex circuit. In one example, two flex circuits are secured to the fabric and there are electrical interconnections between the two flex circuits. The two circuits may be secured to the fabric by a zipper or at least one pair of VELCRO(copyright) patches. The zipper may include conductive teeth and the VELCRO(copyright) patches may include conductive portions to provide the electrical interconnections. The two circuits may include conductive solder pads thereon, and the fabric may include polyester-coated copper fabric, with the solder pads and the coating being melted to formed the electrical connections.
One method of manufacturing a fabric article to include electronic circuitry in accordance with this invention includes assembling a flex circuit to include conductive traces and pads on a flexible substrate, placing a fabric article on a rigid surface, securing the substrate of the flex circuit to the fabric article, populating the flex circuit with electronic components, and securing a protective covering over the flex circuit and the electronic components.
The preferred method of manufacturing a clothing article to include electronic circuitry includes assembling a flex circuit to include conductive traces and pads on a flexible substrate, placing an article of clothing on a rigid surface, securing the substrate of the flex circuit to the article of clothing, populating the flex circuit with electronic components, and securing a protective covering over the flex circuit and the electronic components.
The preferred electrically active clothing article of this invention includes a flex circuit including conductive traces and pads on a flexible substrate secured to an article of clothing. The flex circuit includes stress relief areas which promote flexure of the flex circuit on the fabric of the article. Electronic components populate the flex circuit and a protective covering is placed over the flex circuit and the electronic components.
This invention also features a method of manufacturing a clothing article with at least upper and lower layers of fabric material to include electronic circuitry, comprising assembling a flexible circuit with traces and pads on a substrate, placing a rigid support surface between the upper and lower layers of fabric material, the rigid support surface comprising a stainless steel plate, and securing the substrate to the upper layer of the clothing article using a hand held ultrasonic horn to bond the substrate to the upper layer.
In another embodiment, this invention features a method for manufacturing a fabric article to include electronic circuitry, the method comprising assembling a flexible circuit to include traces and pads on a substrate, placing the substrate between the fabric article and a protective covering, and securing the protective covering to the fabric article so that the flexible circuit is in pressing engagement with the fabric article and the protective covering. Alternatively, the protective covering may be secured to the fabric article such that at least one edge of the protective covering is unattached, thereby forming a pocket into which the substrate is placed, and the bonding the at least one edge of the protective covering to the fabric article.
This invention also features an electrically active textile article including fabric, a flex circuit including conductive traces and pads on a substrate, at least one electronic component populating the flex circuit, and a protective covering secured to the fabric over the flex circuit and the at least one electronic component such that the flex circuit is in pressed engagement with the fabric and the protective coating.